JPS5930327B2 - power splitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to microwave power combining or splitting devices, and more particularly to microwave power combining or splitting devices, and more particularly to planar broadband microwave power combining or splitting devices suitable for use with any number of striplines or microstrips. Relating to power combining or splitting devices.

In the art, amplifiers using field effect transistors are becoming increasingly attractive for use as microwave power sources due to the relatively wide bandwidths achievable with such transistors.

However, power is limited to devices capable of providing 1 watt of output power in the X-band, which has only recently become available for today's field effect transistors.

In typical applications where a solid state transmitter is desired, it is generally necessary to combine the outputs of several field effect amplifiers by a microwave power combiner to achieve a useful power output.

Any such power coupling device shall provide a maximum of 10 decibels of isolation between its input and output points so that the failure of one amplifier does not significantly affect the operation of the remaining amplifiers; It must also be symmetrical to avoid phase and amplitude imbalances.

Generally, many known power combining devices are in the form of T-connected planar arrays, thereby making the number of input points equal to an integer bundle of two.

Thus, for example, if the outputs of nine field effect transistors are to be combined, a T-connected array with 16 input points is required.

Such coupling devices are clearly undesirable in applications where space is at a premium, such as in missiles and aircraft.

Furthermore, if such an array were to provide power to the "input" point and extract power from the "output" point, the 9:1
7 of the 16 ``output'' points must be terminated with a matched load, which accounts for 16 times less of the applied power. 7 will be consumed.

E. G. Wilkinson (E. J. Wi.) in I.R.E. Transactions Microwave Theory and Techniques, Vol.
``An N-Way Hybrid Power Divider'' (1kinson)
Known power dividing devices, such as those described in the document entitled Power Divider ) J, are capable of providing an odd number of output points.

However, because the so-called Wilkinson divider uses circular symmetry, it presents a significant packaging problem in that it cannot be realized in a planar structure except in the case of N=2, where N is the number of output points.

A planar power combiner or divider with an odd number of input and output points is a common T-connected power divider as described in IE Transactions Microwave Theory and Techniques, January 1965. “Split-T Power Divider (5plit-T
This can be realized in combination with a so-called T-divided power device as described in the document entitled Power Divider) j.

Again, such a combination requires considerable space for packaging and exhibits a large insertion area.

With this background of the invention in mind, it is an object of the invention to provide an improved planar power combining or splitting device with an arbitrary number N of input and output points.

Another object of the invention is to provide a power combining or splitting device with very compact packaging characteristics.

Generally speaking, these objects of the present invention are aimed at connecting one port (which can be either an input port or an output port) through N high impedance transmission lines made in the form of striplines or microstrips. This is achieved by providing a planar network with N ports (which act either as output ports or input ports) connected to the output ports (acting either as output ports or input ports).

These N transmission lines have a characteristic impedance that is their impedance multiplied by N2 for loads connected to the N ports.

When these N transmission lines are used as a power coupling device, it is desirable that the length be a quarter wavelength at the center band frequency.

Furthermore, isolation resistors are connected between the N transmission lines.

With such an arrangement, the relative phase of the signals passing through the planar network is maintained, the N ports are isolated from each other, and the available power between one port and the N ports is A split or a combination is performed.

It is used as a power combiner when power is applied to each of the N ports, and as a power divider when power is applied to one port.

The present invention will be described below with reference to the drawings.

In FIG. 1, a flat dividing device 10 (hereinafter often simply referred to as a divider 10 when the input power is to be equally divided between seven output points (ports), that is, when N=7) is shown. ) is shown here as including a network disposed on a planar surface, referred to as dielectric material 12.

The network is formed by depositing or printing a conductive material (here copper) on a portion of the surface of dielectric material 12 by any conventional method.

A conductive coating 26 is applied to the opposite side of the network.

Such a dielectric material may be, for example, a material known as "Duroid 5880 J" manufactured by Loggers Corporation of Candela, AL.

This network consists of seven output arms 141, 142...
...14□ and a single input arm 16.

Output arms 141, 142...14□ (each of these is here a section of 50 ohm transmission line)
are N high impedance transmission lines 18 as shown. , 18□ .

These high impedance transmission lines 18□, 18□...
...The impedance of 18□ is determined by the method described later.

The characteristic impedances of the output arms 141, 142...14□ and the input arm 16 are assumed here to be equal to 50 ohms to match common coaxial cables, but if the impedances connected to them are different. It is different for

Alternatively, other microstrip circuitry can be coupled to splitter 10, as described below.

Arms 141°142...1 as shown
Isolation resistor 200, 202...205 between 4□
is provided.

Such a resistor 20. . 20□...205 are attached to the arms 141, 142...14□ by any conventional method, here solder.

Isolation resistors 201, 20□...205 are connected to high impedance transmission line sections 181, 18 as shown.
. . . 18 □ at the inner ends of the arms 141, 142 . . . 14 □.

It is noted here that the high impedance transmission line sections 181, 182, .

On the other hand, the lengths of arms 141, 142, . . . 14° and 16 are not critical; their lengths are simply chosen to provide packaging convenience.

However, it is noted that arms 141, 142...147 are preferably of equal length in order to maintain phase symmetry.

What is noteworthy here is that arms 14, . 14□...
...The free end of each one of 147 is the end point (port)
Although in practice each such endpoint is usually connected in a known manner to a connector (such as a coaxial connector) so that the intended power splitting device can be connected within the circuit between the power supply and the seven loads. This means that it will be easy to connect to.

It is noted here that FIGS.
The splitting device shown in the figure is designed so that the number of input points is 2.
There are seven output arms just for the purpose of illustrating the fact that it is not necessary that N=7.

Referring specifically to Figure 1A to see what the symbols 2°, R, and Ri mean, in an N:1 splitter with an optimal voltage standing wave ratio, a high impedance quarter-wave line The value Z of the characteristic impedance of each one.

It is shown that Zo=RN3A Equation (1) (where N is the number of output arms).

It is also known that adjacent output points are interconnected with resistors Ri of equal value.

Z, which is the characteristic impedance of each one of the high impedance quarter-wavelength gates.

The values of and Ri are selected taking into account the uniformity of isolation between the input/output point voltage standing wave ratio N of output points.

Z produced the lowest input and output voltage standing wave ratio (less than 1.05 at the center band frequency).

It has been found that the values of and Ri give relatively wide variations in the isolation between the various output points, ranging from 10 dB to 28 dB.

The distribution of separation between output points is Z.

and J can be made more uniform with a corresponding increase in the input and output voltage standing wave ratios.

Table 1 below shows Z for the case N=2 to N-10 that yields the lowest input and output point voltage standing wave ratios.

and the value of Ri. If we refer to Figure 2 here, we can see that
- A typical wideband power combiner 40 (hereinafter often simply referred to as combiner 40) capable of providing 5 watts of output power in the band includes an input power distribution section 42;
It is shown as including a bank 44 of field effect transistors, and a power coupling section 46.

Power distribution section 42 is here basically a circuit (N=6) power splitting device as described above in connection with FIGS. 1 and 1A.

However, the power distribution section 42 in this case is constructed using microstrip technology with two different dielectric substrates 48,50.

Here, as in Fig. 1, the duroid (Duroid)
The dielectric substrate 48, which is an oid), supports one 50 ohm input line 52 and six high impedance quarter wave line sections 541...546.

A dielectric substrate 50, here alumina, supports six 50 ohm output lines 561...566.

50 ohm output line 56. ...566 are made of alumina to reduce the width of these lines and make them more consistent in width with the high impedance quarter-wave line sections 541 ...546. is made on top.

High impedance quarter wave line section 5 on board 48
4...546 and the 50 ohm output lines 561...566 on the board 50 may be made using common thermocompression bonded ribbons (not referenced). can.

Incidentally, the 50 ohm output line 562.563.5
64 and 565 are 50 ohm output lines 56□, 566
It is noteworthy that it is said to be curved so as to maintain the same electrical length as .

Isolation Resistor 661, a model CR chip resistor manufactured by EMC Technology Inc., 1300 Arch Street, Philadelphia, Penn. 19107.
665 is the 50 ohm output line 56 as shown.・・・・・・566 spaces are provided.

The values of isolation resistors 661...665 are determined from Table 1.

50 ohm output lines 561...5 to assist in installing isolation resistors 661...665
A conventional bonding pad (not shown) is provided on each of 66.

Such a pad is a 50 ohm output line 561...
...consists of metal tabs protruding from each side stop of 566.

The bank 44 of field effect transistor (hereinafter referred to as FET) amplifiers consists of six identical 1 Watt transistors (FET6).
21...626).

An input matching circuit 58 for each of these amplifiers.・
...586 and output matching circuit 601...
- 606 is formed on an alumina substrate (not referenced) using microstrip fabrication techniques.

FET621...626 is the input matching circuit 58,
...586 and output matching circuit 601...
... 606 (not referenced), mounted in any conventional manner on the metal ridges 64 disposed between the substrates (not referenced).

The appropriate one of the electrodes from each of the FETs 62□...626 is connected to the respective input matching circuit 58 using any conventional method, here using low temperature indium solder.
□...586 and output matching circuit 601...
...It is attached to 606.

What is noteworthy here is the FET 621...6
The circuitry required to bias each of 26 is not shown to avoid complicating the drawing.

The power output from each of the six FETs 621...626 is combined within power combining section 46.

This power combining section 46 is of the same design as the power distribution section 42, except that these FEs are used to combine an amplified portion of the radio frequency energy at a single endpoint.
It is connected to T like a mirror reflection.

In this way, the 50 ohm input line section 721...
...726 is fabricated on the alumina substrate 74, and on the other hand, the quarter wavelength high impedance line section 761.
...762 as well as the 50 ohm output line 78 are fabricated on the duroid substrate 80.

Isolation resistors 82,...825 are power distribution section 4
It is the same as that used in 2.

It will now be readily appreciated that the electrical length of the electrical path from the 50 ohm input line 52 to the 50 ohm output line 78 is equal to maintain the amplified signals in the 50 ohm output line in phase with each other.

Although a preferred embodiment of the invention has been described, those skilled in the art will appreciate that the power splitting or combining device could just as easily be made using stripline fabrication techniques.

Furthermore, the power splitting or combining device can be designed with other than 50 ohm input or output lines, and the number N or output points can be any number within very wide limits.

Also, a resistor with twice the desired resistance value can be installed in parallel to increase the power handling capability of the isolation resistor.

Therefore, the following can also be realized as specific examples of the present invention.

(1) A radio frequency signal is divided into N equal paths, each part of the signal thus divided is fed to a different one amplifier device for amplification, and each of the thus amplified signals is A radio frequency amplifier adapted to be fed through an equal path to a common output terminal,
a first having one input point for receiving the radio frequency signal to be amplified and N number of output points, the electrical lengths from the input point to each one of the output points being equal; (b) N field effect transistors each connected to a different one of N output points in the first printed circuit; and (c) N field effect transistors each connected to a different one of N output points in the first printed circuit.
has a number of input points and one output point, the electrical length from each one of these input points to the output point is equal, and a different one of these input points has a number of input points of the number N. a second printed circuit to which the output electrodes of each one of the field effect transistors are connected.

(2) The radio frequency amplifier according to (1) above, wherein isolation means is provided between each output point of the first printed circuit and between each input point of the second printed circuit.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a printed circuit of a planar N-way power splitting device according to the invention, FIG. 1A is a circuit diagram of the printed circuit of FIG. 1, and FIG. 1 is a somewhat simplified plan view of the power coupling device; FIG. 10: Split device, 12: Dielectric material, 141-14□: Output arm, 16: Human power arm, 181-187: High impedance transmission line, 201-205: Isolation resistor, 4
0: Power coupling device, 42: Input power distribution section, 44: Field effect transistor bank, 46: Power coupling section, 48
, 50: dielectric substrate, 52: input line, 541-5
46: High impedance quarter wavelength line section, 561
~566: Output line, 581~586 two-person matching circuit,
60□~6o6: Output matching circuit, 621~626: Field effect transistor, 66,~665: Isolation resistor, 72
1 to 726: Input line section, 74: Alumina substrate, 76
1 to 762: quarter wavelength high impedance line segment,
78: Output line, 82, ~825: Isolation resistor.

Claims (1)

Claims: 1. One input port for receiving radio frequency energy in a band consisting of a source of radio frequency electromagnetic energy, having a printed circuit covered on one side with a conductive coating and on an insulating substrate on the other side. and N output ports for distributing this energy to an integer N of loads greater than 2, the power splitting device having: (a) connected to the input port and matched to the characteristic impedance of the electromagnetic energy source; a first printed transmission line having a characteristic impedance and having a free end; (b) having one end connected to each of said output ports and a free end, each matched to the characteristic impedance of a corresponding one of said loads; (c) interconnecting a free end of the first transmission line and a separate free end of each of the N output transmission lines, each of the loads having a characteristic impedance of N transmission lines having characteristic impedances a factor of N2 smaller than the characteristic impedances of their counterparts, each having an electrical length equal to an odd multiple of one-quarter of the radio frequency energy at the center of said band; ) (N-1) isolation resistors connected between the connection points of each pair of the N transmission lines and the N output transmission lines;